As this sort of elemental analyzer, there is one that holds a graphite crucible, which contains a sample, between a pair of electrodes in an extraction furnace; directly applies voltage to the crucible to thereby heat the crucible and the sample inside the crucible; and analyzes sample gas generated by the heating to analyze elements contained in the sample.
More specifically, the above-described elemental analyzer is configured such that the extraction furnace is connected with an introduction flow path for introducing carrier gas having a constant flow rate, and mixed gas of the sample gas generated in the extraction furnace and the carrier gas can be led out from inside the extraction furnace to a lead-out flow path. Further, in an elemental analysis part provided in the lead-out flow path, concentration measurements of carbon monoxide (CO) and nitrogen (N2) contained in the mixed gas are made to thereby analyze what elements are contained in the sample (see Patent Literature 1).
Meanwhile, in the case of a high concentration sample such as oxide or nitride, when heating is performed in the extraction furnace, a large amount of carbon monoxide (CO) or nitrogen (N2) is generated as compared with other materials. As a result, the carrier gas is introduced into the extraction furnace at the constant flow rate, and therefore a concentration measured in each detection part exhibits a high concentration peak within a short time as indicated by a dashed line in a graph of FIG. 4.
That is, in the case of making an elemental analysis of the high concentration sample, as both of a CO detector and an N2 detector used in the elemental analysis part, ones that can cope with high concentration measurements should be selected; however, on the other hand, the detectors that can be make the high concentration measurements tend to have lower sensor sensitivity. Accordingly, as indicated by the dashed line in FIG. 4, in the case where a detection time is short and the peak-like concentration change occurs, it is difficult to make the concentration measurements with accuracy.
In response to such a problem, there is an elemental analyzer 100 that is configured to increase measurement accuracy by, as illustrated in a schematic diagram of FIG. 3, in the lead-out flow path L2, providing a buffer tank B in a stage prior to the elemental analysis part 3 to blunt a profile of the concentration of the sample gas contained in the mixed gas and also increase the detection time in the elemental analysis part 3 as indicated by a solid line in FIG. 4.
However, in the case of providing the buffer tank B as described, corresponding capacity should be ensured inside a housing of the elemental analyzer 100, and therefore there arises a problem of increasing in size of the analyzer. Although the presence of the buffer tank B enables the elemental analysis of the high concentration sample to be made with accuracy, in the case of a low concentration sample, the presence of the buffer tank B prevents the detection because a concentration peak is made too low, or for another reason. That is, the above-described elemental analyzer 100 becomes an elemental analyzer specialized in high concentration samples, and therefore in the case of desiring to analyze a low concentration sample, another elemental analyzer should be prepared.